<?php
function is_mobile(){

    // returns true if one of the specified mobile browsers is detected
    $regex_match="/(nokia|iphone|android|motorola|^mot\-|softbank|foma|docomo|kddi|up\.browser|up\.link|";
    $regex_match.="htc|dopod|blazer|netfront|helio|hosin|huawei|novarra|CoolPad|webos|techfaith|palmsource|";
    $regex_match.="blackberry|alcatel|amoi|ktouch|nexian|samsung|^sam\-|s[cg]h|^lge|ericsson|philips|sagem|wellcom|bunjalloo|maui|";   
    $regex_match.="symbian|smartphone|midp|wap|phone|windows ce|iemobile|^spice|^bird|^zte\-|longcos|pantech|gionee|^sie\-|portalmmm|";
    $regex_match.="jig\s browser|hiptop|^ucweb|^benq|haier|^lct|opera\s*mobi|opera\*mini|320x320|240x320|176x220";
    $regex_match.=")/i";       
    return isset($_SERVER['HTTP_X_WAP_PROFILE']) or isset($_SERVER['HTTP_PROFILE']) orpreg_match($regex_match, strtolower($_SERVER['HTTP_USER_AGENT']));
}

/*
allow the user a way to force either the full or mobile versions of the site - use a GET parameter on requests:
include likes to both versions of the site w/ the special force mode parameters, 'mobile' and 'full':
<a href="http://www.example.org/?mobile">View Mobile Site</a>
<a href="http://www.example.org/?full">View Full Site</a>
Always check for 'mobile' or 'full' parameters before accounting for any User-Agent conditions:
*/
if ($_GET['mobile']) {
 $is_mobile = true;
}
if ($_GET['full']) {
 $is_mobile = false;
}
if($is_mobile) {
    //it's a mobile browser, do something
    header("Location: http://www.yoursite.com/mobile");
} else {
    //it's not a mobile browser, do something else
    header("Location: http://www.yoursite.com/desktop");
    // or instead of a redirect, simply build html below
}
?>